Gelatin subbing compositions having antistatic properties



Patented Feb. 8, 1949 GELATIN SUBBING COMPOSITIONS HAVING ANTISTATI CPROPERTIES Frank J. Kaszuba, Binghamton, N. Y., minor to General Aniline& Film,,Corporation, New York, N. Y., a corporation of Delaware NoDrawing.

This invention relates to photographic film, and more particularly togelatin subbing compositions having anti-static properties.

Considerable dimculty has been encountered in the manufacture ofphotographic film due to the accumulation of electrical charges on thefilm. In one step of the manufacture of photographic film, a film baseis coated on one or both sides with a subbing composition which usuallyconsists of a dispersion of gelatin in a. suitable solvent or solventmixture, so as to facilitate the adherence; or anchorage, of one or moreof the photo-sensitive, non-curling or anti-halation layers. When i sucha laminate is wound into a tight roll and subsequently unwound, asduring a coating operation, considerable static electricity is generatedand spark discharges readily occur. li/iairiifestations of these chargesare glow discharges which after development of the coated and exposedfilm show up as black streaks or lines, or as irregular iogged patternsin the emulsion layer. Attempts have been made to overcome static insuch laminates by the incorporation of substances into subbingcompositions which are electrolytes or possss hygroscopic properties.-The function of these substances is to impart conductivity to thecompositions which reduce static charges on a photographic film baseduring coating of the Application December 17, 1946, Serial No. 716,881

7 Claims. (Cl. 103-135) 2 As suitable examples of aliphatic amides, thefollowing may be mentioned:

For-mamide Diethyl iormamide Methyl ethyl formamide Acetamide Dimethylacetamide Methylol acetamide Ethylol acetamide Propionamide Dimethylpropionamide N-methyi-N-hydroxyethyl-acetamide These amides areincorporated into any gelatin subbing composition containing gelatin,water, dispersing medium, such as an organic acid, 1. e., acetic acid,and the like, and an organic solvent or a mixture of such solvents. Theamount of these amides, which may be employed as an antistatic medium,may; range fromabout 0.5% to 10%, and preferably from 1% to 3%. Thegelatin may range from about 0.5% to 1.5%, preferably from about 0.75%to 1.0%, the balance being water, gelatin dispersing medium, and anorganic solvent or mixture of such solvents. All proportions are byweight.

The anti-static gelation subbing compositions are prepared by adding theamide to a gelatin dispersion containing gelatin, water, and adispersing medium, and thereafter adding the dispersion to an organicsolventor mixture of such sensitive silver-halide emulsion; non-curl, orantihalation layers. 7

Further objects will appear hereinafter.

These objects are accomplished by the present invention byincorporating, into any gelatin subbing composition, an aliphatic amideof the following general formula:

solvents, or by adding the amide to the finished gelation subbingcomposition, 1. e., containing the organic solvent or mixture thereof.Slight warming and agitation will facilitate the dissolution of theamide. The solution thus obtained is depos ited on one or both sides ofa film base in any convenient manner, the subbing operation preferablybeing carried out in connection with, or as -a part of, the process ofmaking the film-support itself. The gelatin subbing solutions made up asabove-"described are clear dispersions.

The film-bases used in accordance with this invention are the cellulosederivatives, e. g., cellulose nitrate, cellulose acetate, and otherlower fatty acid esters of cellulose including simple and mixed esters,such as celluose propionate, cellulose butyrate, celluloseacetate-propionate, cellulos acetate butyrate, and the like, ethers ofcellu- T lose, such as the ethyl ether, benzyl ether, and the like, andthe fusible, water-insoluble, synthetic linear superpolymers used forfilm elements as described inUnited States Patents 2,071,250-2-3 and2,130,948. v It will be appreciated that each 'diflerent' type ofcellulose ester, ether, and mixtures thereof, in-

cluding. the synthetic linear superpolymers, requires a slightlydifferent solvent or solvent combination. The solvent or solvent mixtureemployed must be such that it will have a solvent or at least asoftening or swelling action on the film base so as to stick or anchorthe gelatin upon the area of the support which has been softened orswollen. For example, with a cellulose acetate base a low molecularweight alcohol, e. g.. methanol, ethanol, and-the like, or a ketone,such as acetone or a mixture of 3 parts alcohol to one part of acetonemay be employed. With cellulose ace- .tate-propionate film base, analkyl ester, such as,

it be an organic acid, heterocyclic nitrogenous.-

base, lactone, or the like, disperses the gelatin in water, and thesolvent or solvent mixture wets or After the subbing layer had dried,the usual l Bht-sensitive emulsion layer was coated directly thereon.Durlngthe coating of the llIht-sensitive emulsion upon the subbed baseno static electricity was generated. After exposure and processing theemulsion adhered tenaciousiy to the cellulose acetate film support, andthe developed film showed no black streaks or lines.

Example III A film base prepared from poly (vinyl chloridevinyl acetate)was coated with the following subbing composition:

Gelatin 0.5

Water 2.5 Acetic aci 1.5 Dim'ethyl formamide. 1.5 Methanol 32.0 Acetone62.0

After the subbing layer had dried, the usual light-sensitive emulsionlayer was coated directly thereen- During the coating of thelight-sensitive emulsion upon the subbed base no static I electricitywas generated. After exposure and bites into the cellulose derivative orother materials employed as a film base. The term gelatin dispersed in asolvent for saidsupport as used in the claims should be construed toembrace these dispersing mediums and solvent or'solvent mixture. baseand their solvent properties are known, no difliculty is presented inselecting a. suitable solvent or solvent mixture for use in the subbincompositions.

The following specific examples illustrate several of the variousmethods of applying these amides as'anti-static agents in gelatinsubbing compositions, and it will be understood that these examplesmerely represent the preferred embodi ments and are not to be consideredas limitatlve.

Example I A film base of cellulose acetate was coated with the followinggelatinous substrating composilight-sensitive emulsion layer was coateddirectly thereon. During the coating of the light-sensitive emulsionupon the subbed base no static electricity was generated. After exposureand processing the emulsion adhered tenaciously to Since the materialssuitable for film Example IV Parts Gelatin 1.5 Water 15.0 Salicylicacid, 0.5 Diamyl phen l 3.5 Formamide 1.5 -Methanoi 78.0

the cellulose acetate film support, and the deveiopcd film showed noblack streaks or lines.

Example I! A film base of cellulose acetate-propionate havprocessing theemulsion adhered tenaciously to the cellulose acetate film support, and,the developed film showed no black streaks or lines;

The foregoing composition was found to be excellent as a sub for asynthetic linear polymer film base of the type described in UnitedStates Patents 2,071,250-2-3 and 2,130,948.

The-subbed photographic film bases produced according to the presentinvention, in addition to preventing the accumulation of staticelectricity when unwound during a coating operation, were found to bevery satisfactory from the standpoint of physical requirements, such as,high strength, flexibility, and good water-resistance.

The small quantity of the amide, which may remain with the gelatin afterevaporation of the water and organic solvent from the subbingcomposition, has no adverse efiect upon the lightsensitive emulsionlayer, nor has the subbing composition any adverse effect upon the containers in which it is stored, or upon the coating equipment employed.

It will be understood that wherein the claims appended hereto the term"subbing is used, that such is intended to include the operation ofapplying a subbing layer from any one or the subbing compositionsprepared in accordance with a the present invention.

While the present invention has been described in considerable detailwith respect to certain preferred materials, it is understood that theclass of gelatin dispersing agents, solvents, or mixture of suchsolvents is not limited thereto and that numerous variationsandmodifications described in the foregoing specification may be made. Asfor example, a mixture of two or more of the amides may be employed asanti-static agents.

- Similarly, a film support maybe coated on both sides with the subbingcompositions prepared in accordance with the present invention for thewherein R'is, a member selected from the class consisting of hydrogenand an alkyl group of not more than 3 carbon atoms, R1 is a memberselected from the class consisting of hydrogen, an alkyl group of notmore than 2 carbon atoms, and an alkylol group of not more than 2 carbonatoms,

and R2 is a member selected from the class consisting of hydrogen and analkyl group of the same value as R1.

2. An anti-static gelatin composition suitable for the subbing of aphotographic film support, which comprises a gelatin subbing compositioncontaining from 0.5 to 1.5% of gelatin, from 1.33 to 15% of water, from78 to 95.4% of a solvent for said support, and 0.5 to 10% of formamide.

3. An anti-static gelatin composition suitable for the subbing of aphotographic film support, which comprises a gelatin subbing compositioncontaining from 0.5 to 1.5% of gelatin, from 1.33 to 15% of water, from78 to 95.4%.01 a solvent for said support, and 0.5 to 10% of acetamide.'

4. An anti-static gelatin composition suitable bing oi a photographicfilm support which consists of the following constituents:

Parts by weight Gelatin 0.73 Water 1.33 Acetic aci 1.20 Formamide 1.34Methanol 75.53 Acetone 19.87

6. A gelatin composition suitable for the subbing of a photographic filmsupport which consists of the followingconstituents:

. Parts by weight Gelatin -4 1.0 Water 2.5 Acetic acid 1.5 Acetamide I1.0 I Methanol 74.0 Methyl acetate 20.0

7 l 7. A gelatin composition suitable for the subbing of a photographicfilm support which consists of the following constituents:

FRANK mxaszimA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,101,574 Dangelmajer Dec. 7,1937 2,225,604 Lubs Dec. 17, 1940 2,240,470 Swan Apr. 29, 1941 2,313,570Nadeau Mar. 9, 1943 2,341,877

Middleton et a1 Feb. 14, 1944

